Reproduction of sound



Patented Sept. 8, 1936. 2,053,396

A UNITED STATES PATENT OFFICE REPRODUCTION OF SOUND John Eggert.Leipzig-Goldie, and Richard Schmidt, Dessau, Germany, asslgnors to I. G.Farbenindustrle Aktiengesellschaft, Frankfort-on-the-Main, Germany NoDrawing. Application March is, 1934, Serial No. 716,006. In Germany May8.

4 Claims. (Cl. 274-46) Our present invention relates to a process forgate is preferably led to a device by which the the reproduction ofsound. wetting liquid is stripped oil and the film is dried.

One of its objects is an improved process for What we claim is: thereproduction of sound. Further objects will 1. In the process ofreproducing sound from 6 be seen from the detailed specificationfollowing a photographic sound record the steps which hereafter.comprise coating the film having an emulsion According to this inventionwe have found that layer and a support and being scratched, at most, theundesired ground noise in the reproduction in a minor degree in thebreadth of the sound of photographic sound records is considerablyrecord .on at least one side with a liquid being 10 reduced by coatingthe film with a thin layer of uninflammable at the temperatureprevailing in 10 a liquid which is uninfiammable at the temperathe gateof the reproducing apparatus and havture prevailing in the gate of thereproducing ing -a refractive index approximately equal to apparatus andhaving a retracting index which is that of the support prior toreproduction, reapproximately the same as that of the support. producingthe sound while the liquid is applied The effect of the invention willbe appreciated to the film, and removing the liquid from the whenconsidering that this holds true already for film after reproduction.

the reproduction of sound records which are 2. In the process ofreproducing sound from a played for the first time and is increased withphotographic sound record the steps which comthe number of performancesinasmuch as it comprise coating the film having an emulsion layer'pensates also for the scratching of the sound and a support and beingscratched, at most, in a 0 track caused by the use of the film. Theappllminor degree in the breadth of the sound record cation of theinvention is particularly useful in on both sides with a liquid beinguninfiammable the case of photographic sound records regisat thetemperature prevailing in the gate of the tered on lenticular film. Withthese films the reproducing apparatus and having a refractive lenticularelements cause considerable ground index approximately equal to that ofthe support noise, even in case of the lenticular elements beprior toreproduction, reproducing the sound ing eliminated by one of the knownprocesses while the liquid is applied to the film, and rebecause theplaning processes do not work as ac-' moving the liquid from the filmafter reproduccurately as it is desirable. The lenticular eletion.

ments may be any of the known kind such as 3. In the process ofreproducing sound from a 30 rounded studs or picots, or cylinder lensesexphotographic sound record recorded on lenticular tending inlongitudinal or transverse direction film having an emulsion layer and asupport and .of the film. being scratched, at most, in a. minor degreethe The films may be wetted on one side only or on steps which comprisecoating the film in the both sides in the breadth of the sound record.breadth of the sound record onboth sides with It is, however, preferableto coatthem on both a liquid being uninflammable at the temperaturesides with a thin layer of liquid. The coating of prevailing in the gateof the reproducing appaliquid may be applied by pad continuously wettedratus and having a refractive index approximatewith the liquid, or itmay be applied by a coatly equal to that of the support prior toreproing roller, or a suitable nozzle or in any other duction,reproducing the sound while the liquid 40 suitable manner. The liqu ds epr f a ly is applied to the film, and removing the liquid easilyvolatile so that they can be removed by from th film after reproduction,

evaporation. Sui ab e liquids for instance, 4. In the process ofreproducing sound from a.

halogenated hydrocarbons such as carbon tetraphotographic s und recordthe steps which comchl id or there may be used animal an s prise coatingthe film which is scratched at most table oils which have no n ncy to rmresin a. minor degree in the breadth of the sound us products whichwould soil the apparatus record on aal ast one side with carbon tetra-If the liquidis nonvolatile it may be removed chloride prior toreproduction, reproducing the by an e y volatile solvent which can essound while, the carbon tetrachloride is applied tilled off f r r ve tcoating q idto thefilm', and removing the carbon tetrachlo- The wettingof the film m y b effected prior ride from the film after reproduction.

to its introduction in the projector or also while i n the projector,for instance, while passing JOHN EGGERT.

through the gate. The film, after leaving the RICHARD SCHMIDT. til!

